This invention relates to a process and apparatus of constructing a water tight underground pile wall in the form of a row of piles in which previous piles are installed every other pile and thereafter subsequent piles are installed between said previously formed piles, both of said piles being connected together.
As for the process of this kind, it has been often employed a process wherein as shown in FIG. 1, in the installation of subsequent piles 2 between previous piles 1 installed at intervals of every other pile, cement paste is jetted under high pressure towards the side of the previously formed pile 1 from the side of the subsequently formed pile and the earth is cut and then the cement paste flows thereinto to form a cut-off film 3 in a portion d between the piles.
In accordance with the prior art process, there sometimes occurs a case where if the vertical accuracy of the previously formed piles 1 and the subsequently formed piles 2 and the execution accuracy of the center of piles are poor, the distance d between the piles exceeds the set value or they extend in skew line to each other, and cement paste by jetting does not reach the side of the previously formed pile 1, thus failing to obtain a complete cut-off film 3.
Also, there sometimes occurs a case, depending on the conditions of the earth, where the earth between the piles may not be cut by the jet cement paste and a case where as shown in FIG. 2, the cement paste is spread along the earth layer around the side of the previously formed pile 1, failing to form the cut-off film 3 connecting the piles.
Moreover, even if the earth is cut by the jet cement paste, there remains many problems in terms of the cut-off properties such that the cut-off film 3 is thin and disconnected as shown in FIG. 3, which is not yet satisfactory.